A friend of mine has the SP101 that I'm trying to get him to trade me; similar dimensions to the 2 or 3" GP100 if memory serves. For a revolver, it's a good concealment gun. I carry a Para P12 .45ACP in an Uncle Mike's IWB. The little Ruger drops right in and fits inside perfectly; it's lighter than the .45 and with a 5-shot cylinder it's not bulky at all. As for leather holsters, the Disantis, Galco and Bianchi are my choice.
One word of note, the Rugers seem to have pretty stiff triggers. They may smooth out over time, but they're a handful (to me anyway) at first. If I were to get one, I'd have a trigger/action job done to shorten the pull for my long fingers, and just lighten it up a bit. I don't like handguns that you have to position in your hand just right in order to fire them; I have a big problem with long DA triggers, and most smaller revolvers seem to have them. For handling out of the box, I much prefer some of the bigger S&W's. My 686 is smooth as glass and has a very light pull compared to the Ruger.
Whatever handgun you choose, make sure it fits you well and can be handled easily. The last thing you want is to be fumbling for a grip when you need to get a shot off, or finding you've pulled the trigger back as far as your hand will allow and the gun needs a little more to fire.
Good luck!
